/Engine/Source/Runtime/Engine/Classes/Components/SkinnedMeshComponent.h
Get delta transform from reference pose based on BaseNode. This uses last frame up-to-date transform, so it will have a frame delay if you use this info in the AnimGraph
the delta transform from refpose in that given space (BaseName)
FTransform GetDeltaTransformFromRefPose ( [FName](API\Runtime\Core\UObject\FName) BoneName, [FName](API\Runtime\Core\UObject\FName) BaseName ) const